Controllable-pitch aeronautical propeller



Jan. 19, 1943.

F. w. CALDWELL ETAL CONTROLLABLE-PITCH AERONAUTICAL PROPELLER Filed Aug. 20, 1938 3 Sheets-Sheet l INVENT FEM Ir ATTORNEY.

Jan. 19, 1943. F. w. ows; ETAL 2,308,488

CONTROLLABLE-PITCH AERONAUTICAL PROPELLER F'i-ld Aug. 20, 19:58 3 Sheets-Sheet 2 AT TORNEY.

Jan. 19, 1943. F. w. CALDWELL ET AL 2,303,483

CONTROLLABLE-PITCH AERONAUTICAL PROPELLER Filed Aug. 20, 1938 3 Sheets-Sheet 3 I928 200 [92c 204 mvzmoks ATTORNEY.

the purpose of disclosing the invention.

drawings, however, are for the purpose of illus- Patente d Jan. 19, 1943 CONTROLLABLE-PITCH AERONAUTICAL: PROPELLER Frank W. Caldwell, Hartford, Erle Martin, West Hartford, and John E. Anderson, Portland, Conn., assignors' to United Aircraft Corporation, East. Hartford, Conn., a corporation of Delaware Application August 20, 1938, Serial No. 225,960 '15 Claims. (01. 170-463) This invention relates to. improvements in controllable-pitch aeronautical propellers and has for an object the provision of means for utilizing hydraulic pressure for controlling the pitch of such a propeller.

A further object resides in the provision of control-means for propeller pitch changing means constructed and arranged to render the pitch setting selectable by the 'pilot of the vehicle upon which the propeller is mounted and to maintain erally indicated at l2, carried and driven by a propeller driving engine, generally indicatedat l4.

The propeller l has two or more blades, as Y indicated at l6, rotatably mounted on respective radially "extending arms I8 of a propeller hub spider 20, and retained in operative position upon the arms of the hub spider by the two part barrel thepropeller blade at the selected pitchsetting.

A still further object resides in the provision, in combination with a hydraulic motor and a manually operable valve for controlling the motor, of motor actuated means effective to cause the motor to follow up movements imparted to the manual valve and maintain a setting corresponding to the existing position of the manual valve;

Another object resides in o the provision of means for transferring motion from one side of the propeller to the other.

Other objects and advantages will be more par-.

ticularly pointed outhereinafter or will become apparent as the description proceeds.

In the accompanying drawings, in which like reference numerals are used to designate similar parts throughout, there are illustrated two slightly different mechanical arrangements for tration only and are not to be taken as limiting member 22 and respective anti-friction.roller thrust bearings, as indicated at 24. Each blade receives within the hollow base end thereof a bushing 26 secured to the blade against relative rotation and surrounded by a ring member 28 non-rotatably associated with the periphery of the flanged portion of the sleeve26 and provided, for a portion of its circumference, with beveled gear teeth 30. The teeth of the gear element 30 mesh with corresponding gear teeth 32 formed upon the inner end'of a rotatable cylindrical member 34 provided with helical or diagonal cam slots 36.

Y sion on one side of the barrel 22. The extension or restricting the scope .of the invention as set forth in the appended claims.

In the drawings, Fig. 1 is a vertical sectional view through the center portion of an aeronautical propeller, a

fragmentary portion of'the propeller driving engine and a propeller pitch controlling valve Fig. 2 is a sectional view on the line 2'-2 of.

Fig. 'l.

iFig; 3 is a sectional view on the line of F g. 1. Fig. 4 is a vertical sectional view through, the front portion of a propeller driving engine and the propeller drive shaft showing a propeller pitch control valve arrangement somewhat different from that shown in Fig. 1 but operating on the same general principle.

Fig. 5 isv a sectional view on the line -5-5 of Fig. 4 and,

Fig. 6 is a side elevational view of the slide "valve element shown in section in Fig. 4.

Referring to the drawings in detail, the numeral l6 generally indicates an aeronautical propeller mounted upon a propeller drive shaft, gen- 3B is provided with helical or diagonal cam slots 411 having an inclination oppositely directed from the inclination of the cam slots 36, and the dome member 42 is mounted upon and secured to this extension 38. of the barrel 22 and-carries at its outer end a closed hydraulic cylinder 44 within which cylinder and the member 36 the piston 46 is reciprocable. The piston 46 is provided with an extended annular skirt portion 43 having integral screw'threaded receptacles 50 which receive and support pins 52 carrying anti-friction bearings 54 and 55 movable in the .cam slots 36 and 40 respectively of the members 34 and 36;

From this description it is apparent that a reciprocable movement of the piston 46 in the cylinder 44 movesthe anti-friction rollers or' cam followers '54 and 56 along the respective oppositely directed cam slots 36 and 40 and thereby causes a rotation of the cam element 34 with respect to the cam element 38. Since the cam element 38 is fixed with respect to the propeller hub barrel 22, this relative rotation causes arotationof the gear element 32 and a consequent rotation of thepropeller blades I6 by reason of the intermeshing of the teeth of the gears 32 and 30. In

order to protect the mesh of the gar teeth 30 and 32 the cylindrical element 34 may desirably be supported in an annular anti-friction bearing 58 supported in the front portion of thehub ,barrel22.

Hydraulic iluid under pressure is supplied to and drained from the space between the head The rotatable cam member 34 is sur-. 'rounded and partly supported by a fixed cylindrical element 38 formed as a cylindrical extenward portion and to prevent the passage of hydraulic fluid. such as engine lubricating oil, from one portion of the shaft to the other. The lubricating oil or other hydraulic fluid is led to the interior of the plug 62 from which it enters the rearward end of the tube 60, through an oil duct 66 extending diametrically of the shaft 64 and connecting at its opposite ends with an annular groove 68 in a sleeve I which surrounds the exterior of the portion of the shaft 64 in which the plug 62 is located. The sleeve I0 is rigidly connected with the shaft and abuts at its forward end against the rearward face of the inner race of the main antifriction bearing I2 which rotatably supports the shaft 64 in the engine I4 and transmits the propeller thrust to the engine. A portion of the sleeve is surrounded by a fixed or stationary oil collector ring I4 provided with channels which coincide with exterior annular grooves I6 and I8 in the sleeve I0 and which are connected by means of radial ports with the interior annular grooves 68 and 80 respectively. Suitable oil seal rings 82, 84 and 86 are disposed between the rings 10 and I4 and located so as to enclose and separate the grooves I6 and I8.

A hole 88 is provided, through a portion of the plug 62 and the adjacent portion of the wall of the propeller shaft 64-and leads from the space within the propeller shaft surrounding the tube 60 to the annular groove I8. The space within the hollow shaft 64 surrounding the tube 60 connects the cylinder space at the rear or left hand side of the piston 46 with the hole 88. Fluid conduits 90 and 92 lead from the annular grooves I6 and I8 respectively to the interior of a valve generally indicated at 94.

The valve 94 includes two concentric annular rotatable members, 96 and 98, rotatably mounted in an annular valve casing I00, all particularly illustrated in Fig. 2. The open upper or outer end of the annular valve casing I00 is provided with a closure plate I02 through-the center ofwhich. extends the manually rotatable valve stem I04 made integral with or rigidly connected to the outer annular valve member 98. The inner annular valve member 96 is rigidly secured to or made integral with the hollow stem I06 which extends from-the valve chamber I08 to the interior of the engine I4. Oil, or other hydraulic fluid under pressure, is led through the valve casing I00 to the'valve elements 96 and 98 through a radial port H0. Oil entering the casing I00 through the port I I0 enters the partly circumferential groove or slot II 2 in the member 98. The

slot H2 extends for approximately one-quarter revolution or 90-degrees about the outer face of the cylindrical skirt portion of the member 98. A similar groove or channel H4 is provided in the outer face of the skirt portion of themember 98 diametrically opposed .to the groove H2. The inner face of the skirt portion of the member 96 is provided 'with quadrant grooves I I6 and H8, separated at their adjacent ends by a valve element I28 and interposed between the quadrant slots or grooves H2 and I I4. The upper ends of the tubes 90 and 92 extend through the valve base plate I20 and are surrounded at their upper ing disposed at an angle to the axis of the shaft ends by depressions I22 and I24 respectively cut into the upper surface of the base plate which depressions are'connected with the-grooves H6 and H8 respectively. With this arrangement hydraulic fluid under pressure from the quadrant groove II2 may be directed into. the groove H6 or H8 depending upon the relative position of the members 96 and 98. If the member 96 is rotated in a clockwise direction with respect to the member-98, as viewed in Fig. 2, the groove H2 will be connected with the groove H6 and the fluid will be directed into the conduit 90. If the member 96 is rotated in an anticlockwise direction with respect to the member 98 the groove I I2 will be connected with the groove I I8 and the fluid will be directed into the conduit 92. When the groove H2 is connected with the groove II6 the groove H8 is connected with the groove II 4 so that fluid may flow from the conduit 92 through the connected groove H8, the port I 26, which is connected with the groove I I8 by movement of the vane element I28 in a clockwise direction, and from the groove I I4 through the drain channel I28a to a sump which may be the interior of the engine. When the valve element 96 moves in a counter-clockwise direction with respect to the member 98 the conduit 90 is connected with the drain channel in a similar manner. From this description it is apparent thatwhenever one of the conduits 90 or 92 is connected with hydraulic. fluid under pressure the alternative conduit is connected with a drain through the valve 94. The conduit 90 is connected with the space at the front end of the piston head 46 through the fixed tube 60 while the conduit 92 is connected to the space at the rear face of the piston head through the interior of the hollow shaft 64. With this arrangement, by proper actuation of the valve 94, the space at either side of the head of the piston 46 may be connected with the hydraulic fluid under pressure and the space at the opposite side simultaneously connected with a drain connection so that the piston may be forced in either direction by the pressure of the hydraulic fluid to rotate the propeller blades I 6 in the propeller hub.

A tube I30 is slidably mounted upon the fixed tube and rigidly connected at its forward end to the center of the head of the piston 46 by suitable means such as the inter-engaging annular shoulders I32 and I34 and the annular nut l36. Preferably anti-leak washers I38 are clamped between the nut I36 and shoulder I34 to prevent the leakage of hydraulic fluid past the piston head between the tubes 60 and I30.

At its opposite end the tube I 30 is rigidly secured to a toothed rack member I40, which may be of the form indicated at I16 in Fig. 4, the teeth of whichmesh with the teeth of a gear element I42 rigidly mounted upon or formed integrally witha rotatable shaft I44 which extends diametrically through the hollow drive shaft 64 and extends at its opposite ends into an annular casing I46 secured upon the front of the engine I4 surrounding the drlve'shaft 64. Shoes I48 and I60 are threaded upon the opposite ends of the shaft I44 by a thread having a relatively steep pitch and each shoe carries an anti-friction ball bear- I44, as indicated at I62. The outer races of the ball bearings constitute rollers bearing against the tapered inner face of an annular ring I64 which is non-rotatable but axially slidable in the casing I46. An axially slidable shaft I66 is connected to one side of the ring I64 and projects through the valve casing Ill to carry arack element I58 the teeth of which mesh with a gear lil on the stem I06. The shoes I48 and I50 3 ing the overlap of the adjacent ends of the slots H2 and H6 until finally the fluid passage be- I tween these slots is closed and the fluid supply slide upon a reactionoi guide member I62 which is mounted upon the shaft 64 and rotatable with that shaftwhich carries the shaft I44, and spring pressed plungers I63 urge the ring 154. in opposition to the force appliedby the rollers Since the tube 130 is rigidly connected to'the piston 46 any movement of the piston-will be imparted to the valve member 96 through the;

mechanism above described so that, with the valve member 38 in a fixed position, any movement of the piston results; in a movement ofthe valve element 96 with respect to the valve element 58 which changes the connection between the source of hydraulic ,fluid, the drain channel and the spaces at the opposite sides of the head of the pistonlfi.

r Operation The stem I04 is manually rotatable and may shut off. If now the pitch of. the propeller changes in eitherdirection due to leakage in the hydraulic system or other reasons, the valve element 96 will be actuated through the above described connection to apply hydraulic fluid to the proper side of the-headof the piston 46 to 7 return thepropeller to the selected pitch setting.

The propeller blades will be maintained at a substantially constant pitch setting until the setting isagain changed by the operator, since the change in pitch setting necessary to actuate the valve and bring about a corrective application of hydraulic :fluid under pressure is substantially be rotated by means of a leverfmoving over a dial or quadrant marked with proper indicla indi- I eating the propeller pitch setting in degrees for each position of the manually movable. lever. By

this device the ilot may select the pitch setting at which he wishes the propeller to operate for any subsequent interval. Thus, for take-off he,

may wish the propeller to operate at a relatively flat pitch, for example, 8 degrees, andafter he; has reached a desired altitudand leveled off] for flight he may wish the propeller to operate at a much higher pitch, for example, 18.. degrees. To obtain the desired pitch setting he' ysimply moves his manual lever to the proper negligible.

' In the form of apparatus shown in Figs. 4, 5 and 6 the same type of propeller may be used as that shownin Fig. 1 and generally indicated by the numeral III and may be mountedupon a hollow propeller driveshaft 65 which is in general similar to the drive shaft 64 of Fig. l but is slightly modifiedto better accommodate the different valve arrangement. The drive shaft 65 is rotatably supported in the nose piece of the engine-I4 against axial movement by the antifridtion "bearing. 12 and is provided with an internal. plug I64 which divides the internal bore of theshaft into a rearward or engine portion, and a'forward or propeller controlling portion, the propeller controlling portion being disposed-to the right of the plug I64 as shown in Fig. 4.. 'lfhe't ubelill extends from the propeller piston head through the forward portion of the internal bore of the hollow propeller shaft 65 to location on the dial or quadrant as indicated by c the indicia marked thereon. This moven'ient of I the manual lever rotates the stem I04 and the valve member 98 to some predeterminedpositionf we will asume for the sake of illustratiom-tliat the pilot hm changed the propellersettingfrom a higher or steeper to a flatter pitch-andthatfl the cams'36 and 4. are so arranged that the "application of hydraulic fluid to the" spaceiin front of or to the right of the piston-4G, as mus--- 1 trated in Fig. 1, reduces the pitchof the propeller. Then. in order to reduce the propeller pitch the conduit SI must 'be connected withthe hydraulic fluid under pressure and the conduit connected through a channel I12 with a port 92 connected drain channel. The valve past the vane I28 but the adiacent ends of the slots II2 and "8 are separated and blocked'off from each other. The conduit 92 is then-connected with the drain channel I28 through the slot I IS, the port I26 and the slot I l4. The pressure'upon the opposite sides of the head of the piston 48 is thus imbalanced and the piston is forced rearwardly, or to the left as .viewed in Fig. 1. Thismovement of the piston, transmitted through inember 88 will then bemoved in a counterclock f wise direction. This movement. separates the;

a cavity in' the plug I64, which cavity isconheated by means of a channel I 66 in the plug 'anda connecting channel IS; in the propeller .drive shaft-with a port I'll! opening to the exterior of the propeller driv shaft at a location which will be explained in connection with the description ofthe follow-up valve mechanism.

"The space within the forward portion of the drive shaft bore surrounding the tube is also lid-,opning .to-the exterior of the drive shaft at a location removed from the location of the port .110 by an amount which will become ap- I parent when theconstructionof-the valve mechanism -is made clear. The axially slidable tube I30, which is operatively connected at its forward end to the propeller piston, is rigidly connected-at its rearward o1 left-hand end with a rack member I16 the teeth of V which mesh with' theteeth of a gear or pinion element I18 rigidly secured upon orformed integrally with a shaft. l8bwhich. extends diametrically through .th Id'rive-sha'ft 65 and projects at its opposite end beyond the drive shaft to carry the small pinion gears'l82 and I84.

A; valve member, generallyindicated at I86 and particularly illustrated in Fig. 6, is slidably mounted upon the portion of the drive shaft 65 between the crank cheek; I88 and the bearing 12 within the'nose piece of the engine. If necessary the engine nose piece may-be slightly modified in the tube I3l,,rack I40, gear I42, shaft.

m," shoes m, rollers I52, I54, shaft'lity.

rack tiiand gear-16!; rotates the valve member also inthe same direction, gradually decrease order to provide room for the valve mechanism within the nose piece and the shaft 65 may be 'rnade slightly longer within the engine than-the shaft 64 in order to provide a sumclent length of a shaft between the crank cheek I88 and the bear :ingflifupith operation of the improved propeller-controlling valve. The valve-element Ili is cylindrical in form, has a diameter such that it makes a close sliding fit with the exterior surface of the drive shaft 65 and has a length of substantially two-thirds of the distance between the crank cheek I88 and the shaft shoulder I90 which receives the inner race of the main hearing 12. This cylindrical valve member has two pairs of oppositely disposed cut-outs, as indicated at I92a, I922), I920 and -I92d and which may hereinafter be referred to collectively as out-outs I92. These cut-outs are so arranged that the pair I92a and I92b leave portions of the cylindrical member I86 which act as end valve gates I94 and I96 and a middle valve gate I 98. The opposite pair of cut-outs I92c and I92d leave portions of the cylindrical member which serve as end valve gates 200 and.202, opposed to the end gates I94 and I96 respectively, and a middle valve gate 294. In the side walls between the cut-outs I92 the cylindrical member is provided with elongated opposite apertures 206a and 20617 and which may hereafter be referred to collectively as the apertures 206. Each of the apertures 206 is provided along one side thereof with rack teeth which meshwith the teeth of the respective pinion gears I82 and I84. When the valve element I86 is in its limiting forward or right-hand position, as illustrated in Fig. 4, the port I14 is immediately to the right of the valve gate I94, and the port I is immediately to the right of the middle valve gate 204. From the arrangement thus far described it is apparent that the valve member I86 will be moved back and forth along the drive shaft 65. upon a movement of the propeller piston which moves the tube I30 and operates the rack and pinion device, including the rack I16, pinion I18 and pinions I82 and I84. f

A cylindrical sleeve or shield 208 surrounds the valve member I66 and is annularly spaced therefrom. is sleeve is rigidly secured to the front end of the engine nose piece by suitable means, such as the annular flange 2I0 and bolts 2I2, and between the valveelement I86 and the shield 208 there is slidably disposed the manually controllable valve element generally indicated at 2l4. The rearward or left-hand ends of the valve member I86 and the shield 208 are substantially coterminous when the valve member I86 is in its limiting forward or right-hand position, as illustrated, and the rear or left-hand ends of the valve member 2l4 projects beyond the corresponding ends of the inner valve member and the shield and is provided on this projecting end with an annular groove 2I6 which receives the ends of gudge'cn pins 2I8 carried in the ends of a forked yoke 220 pivoted to the engine by suitable means such as the bracket 222 and pivot pin 224. This yoke may be manually actuated by means of the pivoted lever 226 the inner end of which has an operative connection with the adjacent end of the yoke'member, such as thegear sectors 228 carried by the lever, and 230 carried by the yoke member. With this arrangement movement of the pivoted lever 226 moves the yoke member 220 to slide the intermediate valve member 2I4 in-an axial direction between the valve member I86 and the sleeve 208. The cylindrical valve member 2 is provided with two pair of spaced apart-sealing rings, one pair of rings, as

indicated at 232, being located adjacent to the forward or right-hand end of the valve member and the other'pair, as indicated at 234, being located substantially at the mid-section of the cylindrical valve member.

An oil pressure line 236 leads through the sleeve member 208 at a location somewhat to the right of or ahead of the sealing ring 234 when the valve element 2 is in its limiting forward or righthand position as illustrated, and a port 238 extends through the intermediate valve member 2 at a position adjacent to the ring 234 and between the rings 234 and 232.

Operation of the device shown in Fig. 4

The operation of the above described valve mechanism is substantially as follows' The distance between the sealing rings 232 and 234 is slightly greater than the entire travel of the valve member 2 I4 between its limiting right-hand and left-hand positions as viewed in Fig. 4. This means that the annular space between the intermediate valve member 2 I 4 and the sleeve or shield 208, and between the rings 234 and 232 is always filled with hydraulic fluid under pressure. The only outlet for this hydraulic fluid under pressure from the annular space above described is through the port 238. Now if the port 238 is located to the right of the middle valve gate 204 of the inner valve element I86 the hydraulic fluid will flow through'the port I10, channels I68 and I66 to the end of the tube 60 and through the tubev 60 to the space ahead of or to .the right of the head of the piston 46, as viewed in Fig. 1. At the same time the channel I12 connects the space at. the rear or left-hand side of the piston through the interior of the hollow shaft 65 with the annular space between the valve gates I94 and I98 of the inner valve member. A passage" is opened under the above described positions of the valve members I86 and 2I4 at the left-hand end of the valve member I86 to a drain sump, which may be the interior of the en ine, thus connect-- ing channel I12 with drain. The above described connection of the pressure line and drain to the opposite side of the piston 46 will cause a movement of the piston to the left, as viewed in Fig. 1, and a consequent rotation of the propeller blades in one particular direction.

When the port 238 is to the left of the valve gate I98, as viewed in Fig. 4, the hydraulic fluid under pressure will be connected with the channel I 12 and through the interior of the hollow shaft 65 with the left-hand side of the piston 46, as viewed in Fig. 1. while the space at the righthand side of the piston will be connected through the tube 60, the channels I66 and I68. and the port I10 with the annular space between the valve gates 204 and 202. When the valve'element 2I4 is displaced to the left with respect to the valve element, I86 the annular space between the valve gates 204 and 202 will be opened at its forward end to the space between the flange 2 I 0 and the bearing 12 from which space hydraulic fluid may vent through the port 240 to a suitable sump. This connection of hydraulic fluid under pressure. and the drain line to the p ston 46 will cause a movement of the piston to the right as viewed in Fig. l and rotation of the propeller blade in the direction opposite to the direction above mentioned. I

If the valve member 2I4 is moved to t e left as viewed in Fig. 4 the ports 238 will be moved to the left of the valve gates I98 and hydraulic fluid under pressure will be applied to the rear or left-hand side of the piston 46 tending to move the piston to the right as viewed in Fig. 1. This right-hand movement of the piston moves the rack I16 to the right and rotates the plnions I16,

by moving the inner valve member I86 to the left until a neutral position is reached where the valve gate I98 overlaps the port 238 and shuts 2,sos,4 se

of! the oil supply and simultaneouslythe end valvegates 208 and 202 cooperate with the annular shoulders 242 and 248 of the valve member 2 to cut ed the drain connection. The piston 46 will then be locked in position corresponding to the position to which the valve member 2 has been moved. If, because of leakage or other reasons, the piston moves from the indicated position the inner valve member I86 will also be moved to uncover the port 238 in a direc- I tion to apply additional hydraulic fluid under pressure to the advancing fa e of the piston while connecting the retreating face with drain so that the piston will be moved in amount suflicientto.

bring the valve gate I98 backfito the position a I 5 disposed within said drive shaft and operatively connected with said propeller to move inresponse -to the pitch changing movements thereof, and means including a'gear shaft extending transversely through said drive'shaft for transferring the movement of said drive shaft included means to the exterior of said drive" shaft.

j3.'Incombination with a'controllable'pitch propeller, propeller pitchchanging means, a 4 rotatable hollow drive shaft carrying said pro- .peller and said pitch changing means, and means outside of said drive shaft for controlling said pitch changing means, an element included within said hollow drive shaft 'operatively connected with said pitch changing means, and means for transmitting the movement of said element through said drive shaft to said controlling J means. a

in which it closes the port 238,,in which position the valve gates m and 202 shfit off the drain connection. The spaces I92b and I920 are not utilized as connecting passages in the arrangement illustrated but may be utilized if desired by providing additional pressure and drain chan have been illustrated and described by way of example for the purpose of disclosing the in, vention it is to be understood that the invention is notlimited to the particular mechanical arrangement so illustrated and described but that such changes'in the size, shape and arrangement of the various parts may be resorted to as come within the scope of the appended claims.

Having now described the invention so that othersskilled in the art may clearly understand a the same, what it is desired to secure by Letters Patent is as follows.

What is claimed is:

1. In combination with a propeller having bladesmounted for pitch changing rotational movements, a hollow drive shaft supporting and driving said propeller, a hydraulic motor carried by said drive shaft and rotatable therewith operatively connected with said blades to rotate the same for pitch adjustment, a piston in said motor, a-relatlvelystationary source of hydraulic fluid under pressure and a relatively stationary draln' sump, a two part valve, a connection between said source ,andsaid valve, a connection between said sump and said valve and a pair of connections leading from said valve through said hollow drive shaft to opposite sides of said piston,

- registerable ports in the two parts of said valve for controlling the connections between said- ..J4, In combination with a-controllable pitch propeller having a pitch changing hydraulic motor, and a hollow drive-shaft carrying said propeller, a valve outside of said drive shaft for controlling said motor, a hydraulic system con-'- necting said valve with said motor; an element] inside of said drive shaft'operatively connected with said propeller to movein response to propeller pitch changing movements, and means extending through said hollow drive shaft from the interior to the exterior thereof to transmit. the

movement of said element to a'portion of said valve.- 7

5. In combination with a controllable pitch propeller having a pitch changing hydraulic motor, and a hollow drive shaft carrying said propelller, a valve outside of said drive shaft for controlling said motor, -a hydraulic system connecting said valve with said motor, an element inside of said drive shaft operatively connected with said propeller to move in response to propeller pitch changing movements, a rack and pinion device within said hollow. drive shaft opv eratively connected with said' element, a rack andpinion device outside of said drive shaft operatively connected with said valve, and means extending through said drive shaft from the interior to the 'exterior thereof connecting said rack and pinion device inside of said drive shaft with said rack and pinion device outside ofsaid drive shaft.

6. In combination with a prepeuer having a plurality of rotatably mounted blades; means for rotating said blades forpitch adjustment, and

a hollow. drive shaft carrying-said propeller and said pitch adjusting means, a pitch adjustment control means on the opposite side of said propeller from said pitch adjusting means and outside of said drive shaft, and a mechanical motion transmitting connection extending through source and said sump and the opposite sides of said piston, manually operable. means for moving one of said valve parts to control "said connections to move said motor piston in a selected direction, and piston actuated means for moving the other valve part to control said connections to discontinue movement of said piston when saidpiston has moved a distance having a predetenninedrelation to the amount of movement of said manually movable valve part.

the interior of said hollow drive shaft f-rom said pitch adjusting means and through said shaft from the interior to the exterior thereof to an operative connection with said control means.

'7. In combination with a controllable pitch propeller having a pitch changing motor, and a hollow drive shaft carrying said propeller, a mechanism outside of said-drive shaft having a part movable in proportion to the pitch chang-.

' ing movement of said propeller, an element with- 2.-In combination with a controllable pitch propeller having pitch changing means, and a hollow drive shaft carrying saidpropeller, means insaid drive shaftoperativefyconnected with saidpropeller to move, longitudinally of said drive shaft in response to propeller pitch changing movements, a rack and pinion device within said shaft operated by said element, and a rack and pinion device outside of said shaft operatedby said shaft included rack and pinion de- I vice and operatively'connected with the part of said motor.

said mechanism movable in proportion to propeller pitch changing movements.

8. In combination with a controllable pitch propeller having a pitch changing motor, and a hollow drive shaft carrying said propeller, a mechanism outside of said drive shaft having operatively connected with said blades for rotating the same in pitch changing directions, and a source of hydraulic fluid under pressure, means including a portion of said hollow drive shaft connecting said pressure source with said motor,

a valve interposed in said connecting means between said source of hydraulic fluid and said a part movable in proportion to the pitch changing movements of said propeller, an element within said drive shaft operatively connected with said propeller to move longitudinally of said drive shaft in response to propeller pitch changing movements, a rack and pinion device within said shaft operated by said elements, and a rack and pinion deviceoutside of said shaft operated by said shaft included rack and pinion device andoperatively connected withthe part of said mechanism movable in proportion to propeller pitch changing movements, the pinions of both rack and pinion devices being mounted on a single shaft extending through the wall of said hollow drive shaft.

9. In combination with a propeller having blades mounted for pitch changing rotational movements, an hydraulic motor carried by and rotatable with said propeller and operatively connected with said blades for rotating the same in pitch changing directions, and a source of hydraulic fluid under' pressure, means connecting said pressure source with said motor, a valve interposed in saidconnecting means between said source of hydraulic fluid 'under pressure and said motor and comprising a first part movable to various positions between predetermined limits during propeller operation to change the propeller pitch and a second part cooperating with said first part and actuated by said motor to cut off the connection between said pressure source and said hydraulic motor upon a predetermined pitch change responsive to a movement of said first valve part, and means for transferring movements of said pitch changing motor to said second part of said valve.

10'. In combination with a propeller having blades mounted forpitch changing rotational movements, an hydraulic motor carried by and rotatable with said propeller and operatively connected with said blades for rotating the same in pitch changing directions, and a source of hydraulic fluid under pressure, means connecting said pressure source with said motor, a valve interposed in said connecting means between said source'of hydraulic fluid and said motor and comprising a first part movable to various posi-' tions between predetermined limits during propeller operation to change the propeller pitch and a second part cooperating with said first part and actuated by said motor to cut oil the connection between said pressure source and said hydraulic motor upon a predetermined pitch change'responsive to a movement of said first valve part, and means for transferring movemotor and comprising a first part movable to various positions between predetermined limits during propeller operation to change the propeller pitch and a second part cooperating with said first part and actuated by said motor to cut off the connection between said pressure source and said hydraulic motor upon a predetermined pitch change responsive to a movement of said first valve part, and means .for transferring movement of said pitch changing motor to said second part of said valve comprising a rack and pinion device carried by said 'drive shaft and actuated by said motor, a rack and pinion device operatively connected with said second part of said valve, and a connection between said rack and pinion devices to transmit longitudinal rack movements from one device to the other while permitting-rotation of one 'rack with respect to the other.

'12. In combination with a propeller having blades mounted for pitch changing rotational movements, anhydraulic motor carried by and rotatable with said propeller and operatively connected with said blades for rotating the same in pitch'changing directions, and a source of hydraulic fluid under pressure, means connecting said pressure source with said motor, a valve interposed in said connecting means between said source of hydraulic fluid under pressure and said motor and comprising a first part movableto various positions between predetermined limits during propeller operation to change the propeller pitch and a second part cooperating with said first part and actuated by said motor to cut off the connection between said pressure source and said hydraulic motor upon a predetermined pitch change responsive to a movement of said,

' blades mounted for pitch changing movements, a hollow drive shaft supporting and driving said propeller, an hydraulic motor carried by and rotatable with said propeller and having a reciprocable piston operatively connected with said blades for moving them in pitch changing directions, and a source of hydraulic fluid under pressure, means including a portion of said drive ment of said relatively rotatable pitch changing carried by and rotatable with said propeller and 75 hollow propeller drive shaft comprising, a recipshaft connecting said source of pressure fluid with said motor, a valve interposed in said connecting means between said source of pressure fluid and said motor comprising two concentric parts slidably mounted on said drive shaft, means for .moving one of said parts comprising a manually operable lever and a yoke connection between said lever and said one valve part, and means actuating the other of said valve parts to follow up the movements of said one valve part comprising a rack and pinion connection between said other valve part and the piston -of said motor. 4 I

14. Mechanism for transferring pitch changing movements of a controllable-pitch propeller from the interior to the exterior ofa rotatable rocable element within said hollow drive shaft moved longitudinally of said shaft in coincidence with propeller pitch changing movements, a rack and pinion device within said hollow drive shaft actuated by said reciprocable element, a rack and pinion device outside of said drive shaft, and means extending through said driveshaft operatively connecting said internal rack and pinion device with said external rack and pinion device.

15. In combination with a rotatable propeller having blades mounted for pitch changing movements, an hydraulic motor carried by and rotatable with said propeller and operatively connected with said blades for turning the blades in pitch changing directions, and a source of hydraulic fluid under pressure, means connecting said pressure source with said motor, a valve rotatable with said propeller, interposed in said connecting means between said source of hydraulic fluid under pressure and said motor, and comprising a first part movable to various positions between predetermined limits during propeller operation to changethe propeller pitch and a second part cooperating with said first part and actuated by said motor to cut off the connection between said pressure source and said hydraulic motor upon a predetermined pitch change responsive to a movement of said first part, manually operable mechanism relatively stationary with respect to the rotation of said propeller operatively connected with said first valve part for moving the same, and means rotatable with said propeller for transferring movement of said pitch changing motor to said second valve part. A

FRANK W. CALDWELL.

. JOHN E. ANDERSON.

-DISCLAIMER 2,308,488AFran k*WiChldwell; Hartford, Erle Martin, West Hartford, and John E.

nda goiyfPortland, Conn. CONTROLLABLE-PITCH AERONAUEIICAL PRO- rnnnfinz" Patent dated January 19, 1943; Disclaimer filed July 22, 1943, -by the 'assignee, United Aircraft Corporation.

Hereby caters this disclaimer to claims 9, 10, 12, and- 15 of said specification.

[Oflicial 6 m August 24, 1943. 

